Track circuit apparatus for govern



July 18, 1950 v R. M. GILS ON 7 2,515,642

'TRACK CIRCUIT APPARATUS FOR GOVERNING BOTH WAYSIDE AND CAB SIGNALS Filed Dec. 22, 1945 2 Sheets-Sheet 1 HIS ATTORNEY July 18, 1950 WAYSIDE AND CAB Filed Dec. 22, 1945 R. M. GILSON 2,515,642 TRACK CIRCUIT APPARATUS FOR GOVERNING BOTH SIGNALS 2 Sheets-Sheet 2 I DTHI L\F40 8W- E215 --i- BX I 5] (X FWE -1 B cogzmzzed m 41 INVENTOR BobePzM Gz'lJozz BY aim 15 ATTORNEY Patented July 18, 1950 TRACK CIRCUIT APPARATUS FOR GOVERN- ING BOTH WAYSIDE AND CAB SIGNALS Robert M. Gilson, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale,

Pa.., a corporation of Pennsylvania Application December 22, 1945, Serial No. 636,703

2 Claims.

My invention relates to track circuit apparatus, and more particularly to track circuit apparatus for governing both wayside and cab signals.

In railway signaling the track circuit of a track section is supplied in many cases with direct current for energizing a track relay when the section is unoccupied and with alternating current for operation of a cab signal when a train moves through the section. There are well defined operating characteristics prescribed for track circuits and these characteristics are best met in one manner when direct current is used and in a somewhat different manner when alternating current is used. Also, when a track circuit is to be supplied with direct-current for one function and with alternating current for another function, it is in the interest of economy and simplicity that a single source of power is used,

Accordingly, a feature of my invention is the provision of novel and improved track circuit ap-.

paratus for control of both wayside and cab signals.

Another feature of my invention is the provision of improved track circuit apparatus to supply current for energizing a direct current track relay and for operating a cab signal from a single source of alternating current,

Other features, objects, and advantages of my invention will appear as the specification progresses.

To attain theforegoing features, objects and advantages of my invention, I provide a novel circuit network for connecting a source of alternate ingcurrent to the track circuit to supply current through a full wave rectifier for energizing the track relay when the section is unoccupied, and through a half wave rectifier for operation of the cab signal when a train moves through the section and for also reenergizing the track relay when the train vacates the section.

I shall describe five forms of apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1, 2, 3, 4, and are diagrammatic views showing five different forms of track circuit apparatus, each of which forms of apparatus embodies my invention.

In each of the several views like reference characters are used to designate similar parts.

Referring to Fig. l, the reference characters la and lb designate the track rails of a railway over which traffic normally moves in the direction indicated by an arrow, and which rails are formed with a track ection .D-E, the section D-.E being ordinarily one section of a series of sections of a signaling system. The rails la and lb are arranged to be included in a track circuit which also includes a track relay,'cgnnected across the rails at one end of the section anda source of 2 power connected across the rails at the other end of the section.

As here shown, the track relay is a direct cur.- rent track relay DTR, having a winding lil corrnected across the rails adjacent the entrance D of Section The power source comprises two track transformers ETl and ETZ having priemary windings ll and I2, respectively, connected to a source of alternating current, the terminals of which source are indicated BX and CK. This source of alternating current may be a commercial power line supplying 60 cycle alternating current, but preferably the source would supply alternating current of the frequency of the order of 1-00 cycles per e on ch 0 ycle current being e in y ra lwa i n lin systems. It is to be understood that my invention is not limited to alternating current of any particular frequency, and current of an suitable frequency can be used.

The primary windings of transformers ET! and ETZ are connected to the power source through contacts of an approach controlled relay VR, pri mary winding ll of transformer ETl being con,- nected to terminals BX and (IX through an eh.- vious circuit including front contact l3 of approach controlled relay VB, primary winding l2 of transformer ET; being hort circuited through front contact it of relay VB and connected to terminals BX and CK through back contact E5 of relay VR. 'lhus transformer ETI or ET? is supplied with power according as the relay VB is picked up or is released.

The secondary windings of transformers and ETE are connected to the rails at exit end E of the section through a rectifier here shown as a four arm bridge rectifier l9. Secondary winding it of transformer ETl is connected to input terminals ill and iii of rectifier l9 output terminals 2i) and 2! of the rectifier are connected to the rails by output terminal Ell being connected to rail lb through lead wire 22 and output tere minal 2i being connected to rail la through wire 23, secondary winding 24 of transformer ET2, wire 25, resistor 26 and lead wire 27.

It follows that normally, that is, when relay VB is energized and the track section D-e-E is unoccupied, the track relay DTR is energized by full wave rect'med current supplied to the circuit from transformer ETl through the full wave rectifier l9. As shown in Fig. l, winding it presents low impedance to the flow of current because its primary winding i2 is short circuited by front contact M of relay YR. This permits the normal full wave rectified pulsation in the voltage applied across the rails, which is an aid in shunting the track by the wheels and axles of a car, due to the relatively high peaks of the pulsatin voltage for a givenayeragevalue of voltage.

The relay VB. i controlled through an obvious line circuit including front contact 28 of track relay DTR 'and thus the relay VB is energized when the section DE is unoccupied and is deenergized in response to the train entering the section to shunt the relay DTR. With relay VR released to open front contacts I3 and I4 and close back contact I5, power is removed from track transformer ETI and is applied to the track transformer ET2 and half wave rectified current is supplied to the track rails from secondary winding 24 of transformer ET2 through the rectifier I9 serving as a half wave rectifier. When the top terminal, as viewed in Fig. 1, of secondary winding 24 is positive, current flows through wire 23, terminal 2| to terminal 20 of rectifier I9 through the rectifier elements in the forward direction, lead wire 22, rail Ib, train shunt to rail Ia, lead wire 21, resistor 26, and Wire 25 to the other terminal of the secondary winding 24. During the half cycle of the power source that the lower terminal of secondary winding 24 is positive, the flow of current to the track circuit is blocked b the rectifier elements of rectifier I9. Thus, half wave rectified current is supplied to the track circuit and such current is available for inductive operation of cab signals when the section is occupied. When the train moving through section DE vacates the section, the half wave rectified current is also available for initial energization of the track relay DTR, and that relay is Picked up to restore the appanatus to its normal condition.

It is apparent that by proper proportioning of the parts, the apparatus of Fig. 1 will supply full wave rectified current suitable for proper energization of the track relay DTR. when the section is unoccupied and will supply half wave rectified current suitable for inductive operation of cab signals when a train moves through the section, and such half wave rectified current is available for initial energization of track relay DTR when the train vacates the section.

The apparatus disclosed in Fig. 2 is the same as that of Fig. 1, except for the track transformer. In Fig. 2 a track transformer ET3 is provided with a primary winding 29 and two secondary windings 39 and 3|. Primary winding 29 is connected to terminals BX and CX of the power source, secondary winding 30 is connected to input terminals I! and I8 of rectifier I9 through :a front contact 32 of relay VR, and the output terminals of rectifier I9 are connected across the rails at exit end E of the track section, the output terminal 20 being connected to rail Ib through lead wire 22 and output terminal 2| being connected to rail Ia through wire 23, front contact 33 of relay VR, wires 34 and 25, resistor 26, and lead wire 21.

At such time as relay VB. is released to open front contacts 32 and 33, secondary winding 30 is disconnected from the track circuit and secondary winding 3| of the track transformer is connected thereto, the connection including rectifier I9 as a half wave rectifier. During the half cycle the top terminal of secondary winding 3| is positive, current flows through back contact 35 of relay VR, wire 23, terminal 2| to terminal 20 of rectifier I9 through the rectifier elements in their forward direction, lead wire 22, rail lb, train shunt, rail Ia, lead wire 21, resistor 26 and wire 25 to the lower terminal of secondary winding 3 I. During the other half cycle of the power source, the flow of current to the track circuit is blocked by the rectifier elements of rectifier I9.

The relay VB is controlled through a line circuit including front contacts 28 of the track relay 4 D'I'R, the same as in Fig. 1, and consequently full wave rectified current is supplied from secondary winding 30 of the track transformer to energize the track relay DTR when the section is unoccupied and half wave rectified current is supplied to the track circuit from secondary winding 3| for operation of cab signals when a tnain occupies the section. The half wave rectified current is also available to initially energize the track relay DTR and restore the apparatus to normal condition when the train vacates the section.

The apparatus disclosed in Fig. 3 is different from that of the apparatus of Fig. 1 in the arrangement of the rectifier, and to include a shunt path around the rectifier. Primary windings II and I2 of the two track transformers are connected to the power source through contacts of the relay VR the same as in Fig. 1. Secondary winding I6 of track transformer ETI is connected to the outside terminals of rectifiers 8 and 9 in series. The junction terminal of rectifiers 8 and 9 is connected to rail Ib through lead wire 22 and a mid terminal of secondary winding I6 is connected to rail Ia through resistor 26, secondary winding 24 of transformer ET2 and lead wire 21.

Rectifiers 8 and 9 are poled reversed to each other and thus when the track section DE is unoccupied and relay VB is picked up, the track circuit is supplied with full wave rectified current from secondary winding I6 through the rectifiers 8 and 9, and when relay VB is deenergized in response to a train entering the section to shunt track relay DTR, the opening of front contacts I3 and I4 discontinues the supply of full wave rectified current and half wave rectified current is supplied to the track circuit from the secondary winding 24 of track transformer E'I2 through resistor 26, lower half of secondary winding I6, and rectifier 9. However, in Fig. 3, a shunt path including a resistor 36 is connected around the rectifier 9 and resistor 26 through back contact 31 of relay VR, and such shunt path serves to increase the alternating component of the track circuit current so that when the section DE of Fig. 3 is occupied, the half wave rectified current has a large alternating current component for operating the cab signals. Resistor 36 would usually have considerably greater resistance than resistor 26 so that the direct current component of the track circuit current supplied when the relay VB. is released will be of sufficient magnitude to energize the track relay DTR and restore the apparatus to its normal condition when the train vacates the section.

In each of Figs. 1, 2 and 3 it is obvious that a coder can be provided for the apparatus and a coder contact interposed in the connection of lead wire 22 or 21 and the track circuit provided with coded current for operation of a code following track relay and coded cab signals.

The apparatus disclosed in Fig. 4 is different from the apparatus of Fig. 2 in that a coder is provided, the track relay DTR is replaced by a direct current code following relay DTRI, and a reactor and a capacitor are included in the circuit network through which the track transformer is connected to the track rails.

I In Fig. 4, a portion of secondary winding 30 is connected across input terminals I1 and I8 of rectifier I9, the portion of the winding to be used being preselected according to the particular track section to be supplied. The output terminals 20 and 2| of rectifier I9 are connected across the rails by terminal 20 being connected to rail lb through a reactor 38 and lead wire 22; and terminal 2| being connected to rail la through winding 3|, resistor 26, contact 48 of coder CP and lead wire 21. A- capacitor M is connected around rectifier I9 and reactor 38.

Secondary winding 38, in combination with the rectifier I9 and the capacitor 4|, which preferably is of relatively large capacitance, maintain a unidirectional voltage across the capacitor 4| of the polarity indicated in Fig. 4. Secondary winding 3| provides an alternating current component to the track circuit, the path for which includes lead wire 22 from rail lb, capacitor 4|, secondary winding 3|, resistor 26, coder contact 40, and lead wire 21 to rail la. Capacitor 4| is thus a mutual element in the direct current and alternating current supply circuits and acts very much like a battery to provide a direct voltage in series with the alternating voltage with consequent direct current and alternating current components in the current in the rails. The direct current component is eflective to energize the direct current track relay DTRI when the section is unoccupied, and the alternating current component serves to operate a cab signal when a train occupies the track section. The reactor 38 prevents the alternating current component from unbalancing the currents between the two legs of each pair of legs in rectifier I9 and thus prevents any appreciable direct current component in secondary winding 36, and also reduces the ripple in the rectified voltage supplied by secondary winding 30 and rectifier I!) to capacitor 4|.

In Fig. 5, secondary winding 30 of transformer ET3 is connected across the outside terminals of rectifiers 8 and 9 in series and poled reverse to each other. The junction terminal of rectifiers 8 and 9 is connected to rail Ia through resistor 26, coder contact 48 and lead wire 21, and a mid terminal of winding 30 is connected to rail |b through reactor 38 and lead wire 22. Thus a full wave rectified current is supplied to the track circuit from secondary winding 3|) and such current is available to energize track relay DTRI when the section is unoccupied.

Secondary winding 3| is connected across the track rails through capacitor 4|, back contact 42 of approach controlled relay VR and resistor 26. Thus when relay VB is released an alternating current is supplied to the rails from secondary winding 3| and such current is available to operate a cab signal when a train occupies the section. The capacitor 4| serves to block the direct current from winding 3|, and

the reactor 38 serves to prevent the alternating;

current from unbalancing the rectifiers. Thus in Fig. 5, the direct current component and the alternating current component of the current in the rails can be independently adjusted.

Track circuit apparatus such as here disclosed has the advantages that from a single source of alternating current a track circuit is provided at times with a rectified direct current having a relatively small alternating current component for energization of a direct current track relay, and at other times with a current having a relatively large alternating current component for operation of cab signals, this latter current also having a direct current component efl'ective to initially energize the track relay.

Although I have herein shown and described but five forms of track circuit apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In track circuit apparatus for a track section, the combination comprising, a direct current track relay connected to the rails at the entrance end of said section, a first and a second track transformer, an approach relay controlled to a first and a second position through a contact of said track relay, means including a first position contact of said approach relay to connect a primary winding of said first transformer to a source of alternating current, means including a second position contact of said approach relay to connect a primary winding of said second transformer to said source of alternating current, a current rectifier means adaptable of being used either as a full wave rectifier or as a half wave rectifier, a first circuit means to connect a secondary winding of said first transformer to the rails at the exit end of the section through said rectifier means as a full wave rectifier to energize said track relay with full wave rectified current,

and a second circuit means to connect a secondary winding of said second transformer to the rails at the exit end of said section through said rectifier means as a half wave rectifier to supply a half wave rectified current for operation of cab signals.

2. In track circuit apparatus for a track section, the combination comprising, a direct current track relay connected to the rails at the entrance end of said section, a first and a second track transformer, an approach relay controlled to a first and a second position through a contact of said track relay, means including a first position contact of said approach relay to connect a primary winding of said first transformer to a source of alternating current, means including a second position contact of said approach relay to connect a primary winding of said second transformer to said source of alternating current, a full wave rectifier, a secondary winding of said first transformer connected across the input terminals of said rectifier, and means including a secondary winding of said second transformer to connect the output terminals of said transformer across the rails at the exit end of the section, whereby full wave rectified current is supplied to energize said track relay when the section is unoccupied and half wave rectified current is supplied for operating cab signals when a train occupies the section.

ROBERT M. GILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,626,928 Geiger May 3, 192'! 1,692,061 Thompson Nov. 20, 1928 1,963,243 Osmos June 19, 1934 1,985,635 Fleming Dec. 25, 1934 2,045,992 Nicholson June 30, 1938 2,122,382 Reichard June 28, 1938 2,243,671 Ehret May 27, 1941 

